1. Field of the Invention
The present invention relates to a method used in a wireless communication system and related communication device, and more particularly, to a method of indicating physical uplink control channel (PUCCH) resources for a transmission of control information in a wireless communication system and related communication device.
2. Description of the Prior Art
A long-term evolution (LTE) system supporting the 3GPP Rel-8 standard and/or the 3GPP Rel-9 standard has been developed by the 3rd Generation Partnership Project (3GPP) as a successor of a universal mobile telecommunications system (UMTS), for further enhancing performance of the UMTS to satisfy increasing needs of users. The LTE system includes a new radio interface and a new radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes multiple evolved Node-Bs (eNBs) for communicating with multiple user equipments (UEs), and communicates with a core network including a mobility management entity (MME), a serving gateway, etc., for Non Access Stratum (NAS) control.
An LTE-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system. The LTE-A system targets faster switching between power states, improves performance at the coverage edge of an eNB, and includes advanced techniques, such as carrier aggregation (CA), coordinated multipoint (COMP) transmission/reception, uplink (UL) multiple-input multiple-output (MIMO), etc. For a user equipment and an eNB to communicate with each other in the LTE-A system, the user equipment and the eNB must support standards developed for the LTE-A system, such as the 3GPP Rel-10 standard or later versions.
The 3GPP spec has defined the physical uplink control channel (PUCCH) with several formats, as shown in Table 1, for transmissions of certain control information.
TABLE 1Number ofbits perPUCCHModulationsubframe,formatschemeMbit1N/AN/A1aBPSK11bQPSK22QPSK202aQPSK + BPSK212bQPSK + QPSK223QPSK48
In the prior art such as the 3GPP Rel-11 or before, a resource index nPUCCH(2,{tilde over (p)}) identifies resources used for transmission of hybrid automatic repeat request (HARQ) feedbacks and channel state information (CSI) reports over PUCCH formats 2/2a/2b in a wireless communication system supporting a MIMO technology. From the resource index nPUCCH(2,{tilde over (p)}) all resources including frequency band (i.e. resource block) and cyclic shift for transmissions over PUCCH format 2 can be derived. The range of the resource index nPUCCH(2,{tilde over (p)}) is indicated in 3GPP TS 36.331 Rel-11 as follows:
CQI-ReportPeriodic-r10 : :=CHOICE { releaseNULL, setupSEQUENCE {  cqi-PUCCH-ResourceIndex-r10INTEGER (0..1184),  cqi-PUCCH-ResourceIndexP1-r10INTEGER (0..1184)OPTIONAL, -- Need OR  cqi-pmi-ConfigIndexINTEGER (0..1023),  cqi-FormatIndicatorPeriodic-r10CHOICE {
In such a situation, the range of the resource index nPUCCH(2,{tilde over (p)}) is from 0 to 1184.
However, for an enhanced MIMO technology which features finer spatial and frequency granularity, additional channel state information (CSI) reports providing sub-band channel quality indicator (CQI), sub-band precoding matrix indicator (PMI), etc. are required. In such a situation, the UE needs to transmit more bits for the CSI reports. Thus, utilizing PUCCH format 2 for transmission of HARQ feedbacks and CSI reports may be insufficient.
On the other hand, a resource index nPUCCH(3,{tilde over (p)}) identifies resources used for transmission of HARQ feedbacks over PUCCH format 3 for a wireless communication system supporting a CA technology, where the UE is configured multiple cells. The range of the resource index nPUCCH(3,{tilde over (p)}) is indicated in 3GPP TS 36.331 Rel-11 as follows:
PUCCH-ConfigDedicated-v1020 : :=SEQUENCE { pucch-Format-r10CHOICE {  format3-r10SEQUENCE {   n3PUCCH-AN-List-r10 SEQUENCE (SIZE (1..4)) OF INTEGER (0..549)OPTIONAL, -- Need ON   twoAntennaPortActivatedPUCCH-Format3-r10CHOICE {    releaseNULL,    setupSEQUENCE {     n3PUCCH-AN-ListP1-r10 SEQUENCE (SIZE (1..4)) OF INTEGER (0..549)    }   }OPTIONAL -- Need ON  },  channelSelection-r10SEQUENCE {   n1PUCCH-AN-CS-r10CHOICE {    releaseNULL,    setupSEQUENCE {     n1PUCCH-AN-CS-List-r10 SEQUENCE (SIZE (1..2)) OF N1PUCCH-AN-CS-r10    }   }OPTIONAL -- Need ON  } }OPTIONAL, -- Need OR twoAntennaPortActivatedPUCCH-Format1a1b-r10ENUMERATED {true}OPTIONAL,-- Need OR simultaneousPUCCH-PUSCH-r10ENUMERATED {true}OPTIONAL,-- Need OR n1PUCCH-AN-RepP1-r10INTEGER (0..2047)OPTIONAL -- Need OR}
In such a situation, the range of the resource index nPUCCH(3,{tilde over (p)}) is from 0 to 549.
However, if the UE is configured one cell, PUCCH format 3 is not used for transmission, and thus no signalling for PUCCH format 3 is received from the serving base station.
Therefore, how to indicate PUCCH resources for a UE of a wireless communication system supporting an enhanced MIMO technology without changing the 3GPP spec too much is a topic to be addressed and discussed in the industry.